Base "abstract" class creating reports on your data.

Creating reports
Creating a new report is a matter overloading a few key methods
: Return the title - i18n is your responsibility
: Return the description - i18n is your responsibility
: Return a SS_List of the search results
: Return information about the columns in this report.
: Return a FieldList of the fields that can be used to filter this
If you wish to modify the report in more extreme ways, you could overload these methods instead.
: Return a FormField in the place where your report's TableListField
usually appears.
: Return the FieldList representing the complete right-hand area of the
report, including the title, description, parameter fields, and results.
Showing reports to the user
Right now, all subclasses of SS_Report will be shown in the ReportAdmin. In SS3 there is only
one place where reports can go, so this class is greatly simplifed from its version in SS2.